Many modern portable devices (e.g., laptop computers, mobile phones, digital cameras, video cameras, media players, personal digital assistants (PDAs), game console, etc.) include battery packs. Battery packs typically include one or more battery cells coupled to two or more Integrated Circuit (IC) chips (e.g., a microcontroller, analog front-end, etc.) for providing battery cell management and protection and for making charge left measurements.
Many battery packs typically use a Lithium-ion (Li-ion) battery cell, which is essentially a volatile chemical reaction packaged inside a cylinder or prismatic. Potential energy is stored in each cell, and if the battery cell is exposed to conditions outside of its specification the cell could overheat, catch fire or explode. Battery packs typically include fail-safe circuitry for detecting unsafe conditions (e.g., charge or discharge over-currents, short circuits, etc.), and for taking corrective action to prevent damage to the battery cell and/or device, and to protect consumers from exploding batteries and other dangerous events.
When a battery pack is connected to a device, or when the device enables a feature with high power consumption (e.g., a motor), a high current can be drawn from the battery pack for a period of time. These events are part of normal battery operation, and should be managed so that the battery pack and the device are able to maintain stable operation. Ideally, a battery pack should function to protect battery cells from high currents maintained for a long period of time (i.e., longer than normal high current events), since such currents are potentially dangerous to the user and damaging to the battery cells. Such abnormal high current events can be prevented by stopping the high current flow. Stopping the current flow, however, can cause the output voltage of the battery pack to drop to zero or close to zero, resulting in unstable operation of the battery system. It is important, therefore, to distinguish high currents resulting from normal operation from high currents that are potentially dangerous and/or damaging.
Conventional battery packs do not distinguish between high currents resulting from normal operation and high currents that are potentially dangerous and/or damaging. High currents are often treated as potentially dangerous and/or damaging, even if they result from normal operation.